/**
 * alphaNumericPlaindrome should return true if the string has alphanumeric characters that are palindrome irrespective of special characters and the letter case
 * @param {string} str the string to check
 * @returns `Boolean`
 */

/*****************************************************************************
 * What is a palindrome? https://en.wikipedia.org/wiki/Palindrome
 * 
 * The function alphaNumericPlaindrome() recieves a sting with varying formats
 * like "racecar", "RaceCar", and "race CAR"
 * The string can also have special characters 
 * like "2A3*3a2", "2A3 3a2", and "2_A3*3#A2"
 * 
 * But the catch is, we have to check only if the alphanumeric characters 
 * are palindrome i.e remove spaces, symbols, punctuations etc 
 * and the case of the characters doesn't matter
 * 
 * This is one of the questions/projects that we have to solve for the 
 * JavaScript Algorithms and Data Structures course on https://www.freecodecamp.org
 * 
 * Author -- Syed Fasiuddin 
 * https://github.com/SyedFasiuddin
 * 
 ****************************************************************************/

const alphaNumericPlaindrome = (str) => {
    // removing all the special characters and turning everything to lowercase
    let newStr = str.replace(/[^a-zA-Z0-9]*/g, "").toLowerCase();
    // the newStr variable is a string and only has alphanumeric characters all in lowercase

    // making an array of individual characters as it's elements
    let arr = newStr.split("")

    // setting a variable to see if change occurs to it 
    let palin = 0;

    // making a copy of arr with spread operator
    let arrRev = [...arr];
    // you can use arrRev.reverse() to reverse the array
    // or else you can use the below method 

    // iterate through the arr and check the condition of palindrome
    for (let i = 0; i < arr.length; i++) {
        if (arr[i] !== arrRev[arr.length - 1 - i]) {
            // if the string is not palindrome then we change palin varaible to 1
            palin = 1
        }
    }

    // if the string is palindrome then palin variable is never changed
    if (palin == 0) return true;
    else return false;
}


// test cases
// alphaNumericPlaindrome("eye");
// alphaNumericPlaindrome("0_0 (: /-\ :) 0-0")
// alphaNumericPlaindrome("five|\_/|four")
// alphaNumericPlaindrome("A man, a plan, a canal. Panama")


export { alphaNumericPlaindrome }